Internal-combustion engine



April 22, 1930. R. H. DIBLEY w INTERNAL coMBuvsTIoN ENGINE Filed April50, 1927 MM N WH. Hv

W HY Pa tented Apr. 22, 1930 RAYivronn vH. DIBLEoF BATz-Iunsr, NEWso'iJrHWALEs, AUs'rR-AIA INTERNAL-ooivnsnsrrou TENGI NE Applicationfiled April 30,

This 'invention relates to an engine and morepartioularly to the methodof control-1 Chamber Zwhich increase the powerand effi-v oiencythroughout the entire the engine;

speedV range of More specfloally stated theinvention c'oni,

sists in overlapping the intake and exhaust valves of a conventional.sngle-carburetor engine at the upper end of lthe piston scav- Vengingstroke over a greater range than heretofore believed possible. i w' Ithas been found that a depression in the combustion Chamber exists, ormay be made to exist by controlling thel exhaustvalveA opening nl thecombustion chamber duringV the Vexhaust stroke, and that by opening theintakevalve at the beginning or during this depression, combustiblegases are clrawn into the combustion charnber during the upward'moveinent of'theupiston. It istherefore an important object of thisinvention to com- `pletelyscavenge the combustion Chamber before thedownward inovement of the piston for the intake stroke. v,

Another object of the.- invention is to balance'the pressures at Vtheintake'valve, in the combustion Chamber andl at the exhaust valve suchthat exhaust gases drawn into the combustion chamber aremateriallyreduced if not' entirely eliminated during the exhaust istroke hereinafter morefully described.

Other objects and :advantage's will more fully appear from the followingdescription taken 111 connectlon u 1th the accompanying mon IS reachedfand better scavengmgls 0b i dravvings, in whichz' u w Fig. 1 is asectional view thru an internal combustion engine.V

w the :opening and closingof'the intake and exhaust valves and thepressures 1n the combustion Chamber during twocomplete revolutions ofthe -crankshaftV v Fig. 3 1s an'enlarged vlew showing in de- C v A tainvpressure in the intake manifoldat the Fig. 2 is a diagrammaticviewlllustratlng f has reached top dead center,,thus balancing 1927.serial No. 187,'e41.

tail the construction of theinta-ke valve operatingcam. 'o

. Fig. 4' is an enlarged viewshowing in detail the construction oftheexhaust valve operatingoani. fo Fg; 5 isa 'diagrammaticfv-iew showingthe relative, operation of the VoonventionalV present type timing ascompared tomy newj method. i w The Velocity of the reciprocating pistonof an internal combustion engine'varies thru its cycle of movement.V'The piston on its. upward movement progressively increases its speed'untilV it attains a position slightlyV above the center of its stroke,the amount' vof excess above the' center 'of the stroke depending on thelengthl of the connecting rod.,' .Due to therotating movement of thecrankshaft the piston7s velooityvi's retarded beyond center and theinertia ofthe exhaust gases thru the exhaust'valve causes the volumeV'of exhaust gas to .Continue beyond the piston-causing a depression orsubatmospheric;pressure V i within the combustion Chamber which drawsexhaust gases f back -into the combustion chamber. The piston continuingits upward travel overcoines I this depression by fagain building up apressure'within the Chamber. Heretofore if'any .overlappingv of thevalves Was made it'was during this second compresi sion period which'caused a blowbacl: of the eXhaust gases into the intake'passage. VForthis reason very slight overlapping of the intake and exhaust valves hasbeen made;

I have found'that'by overlapping. the intake and exhaust valves over agreater range at topdead center, the degree of which'is i dependent uponthe motor design, having the intalre. valve`. open before or during theldepression,` a` more stable and balancedconditained. g Due to the ramaction of the gas col-l umn` in the intake mani'fold there is a cervalveand-;even assuming atmospher-io'preso 5 sure therein the depression orsubatmosw ,pheric pressure in thecombustionchamber draws in combustiblegases before the /piston theV pressure in the intalze manifold with theV is thus balanced in the combutio'nz cham-4 gases is overcome. Thisbalancing is accomplished by ,a combustible gas rather than anoncombufstibl'e gasv and after the pressure is balanced in thecombustion. chamber 'that pressure balances exhaust pressure thuspreventing their return into the. combustion' chamber. The final upwardmovement of thepiston'., which: :atthis point isshort: audicomparatively slow, further balanees the pressure in the` oomrbustionlchamber with: the exhaust and intake manifol'ds. flh'eV p ressure'-b'er',1 intake manifold an'di eXh-austman-ifold by` ai c'ombustible gas:rather than by' the biproductsof conii'bu'stion from the exl'iau'stline.

The. contraction. of the exhaust gasesd in the exhaust passage :a'dd'edito the' small' ine'rtiafat. idl'e` or' slow speedscreates the depres-lsion' at.` approximately the same place as at' high speeds with greater'ilnertia and relat'mely' small contracti'zon.` i

The abovev description is" ideal? for open throttle: conditions due: t'othe ram pressur'es: in the intalre'manifolid. readily balancing thelow-:pressures in. the: combustio'n chamben butt for closed throttle:conditions'a subaztmospheric pressure condition exis'tswhich does notreadilybalanceand to1=overcomethis con;- dition the: overl'appingperiod" i's' decreased, that; iszthe intakey valve: opens shortly afterth'e' depressiorr. has been reachecl: but before iticeases. 'Duringz theov'enlapping peri'oclf' the intalreva'lve area; i's compa'raiti'vely'"larger than the. exhaustl valve and the intake Valve opens `quri'ekllywhile the exh'aust value" parti-ally closeis quickly withinI certainlifimits, completely'v closing' sloWl-y* so` that' pressureI conditions:are compensazt'edf` for at sl'own andv high speeds$l` o 13 am aware3that some overliapping' of the 'in-take and exhaust valves-l has beenmade but due tothe assumption of a continuoufs'pressure the exhaustpassage and a relatnrely low pressure theint'ake manifold', the overila'pping 'of-V theval-Ves has been slightfto prevent a blow back thrutheintake passage. Itis true that s'light overlappmtg causes' a i blowvback and' that increasing.theover-` la-I'ytheblow back isincreas'edbutfthe latter isV only true for acertain number of'degrees-.

increased power given by the overlapping of the Valves and the wider camnose such loss of power may be sacrificed for quietness in operation. yo

Referri-ng| to the drawing's wherein one form of my in-Vention has beenillustrated,V I haveV shown a conventional engine having an inletmanifold 10, Vexhaust manifold- 12", coinbusti'on Chamber 14 andcarburetor 1'5.V A crankshaft- 116 reoiprocates a piston 18 in vacylinder 20 and a cam'shaft 22, Conventi'onally driven by the crankshaft16' is adapted, thru suitable' conventional Valvek mechanism, to openland close the inlet and exhaust Valves. It is to be understood thatwhile only the in'take valve has been shown the -exhaust Valve'leadingto the exhaust mani'fo'ld 12' is in line withthe intake Valve and forall purposes practically the same.

Referring to Fi'g. 2 a complete cycl'e or twol The ou'terdouble- CircleI28 indicatesthe opening of the exha-ust valve while-the inner doubleCircle' 30 indicates the opening of the int'ake valve. At

the point indicated at'A, the depression' above referred-to occurs andat thisl point the intakevalve opens whereupon the depress-ion isfilledwithv com'bustibl'e gasesithru the in'takeivalve'.`

B indicates the second compressionperiod' of the exhaust stroke'..

Figs-.f 3 and 4 illustrate respectively the construction of the intakecam' and exhaust cam, The dotted lines illustra-te the outline of aconventional cam and' the fulllines illustrate my improved cam The camsmay be considered as`comprising a base Circle' portion, quieti'ng` zone,fl/anl: radius and nose. C indicates the quieting zone for the stand-'ardcam and C' the advanced zone. 'D indioates the valve llft includingthe: fiank radius i and the nose radius of the' standard lcam while D'mdic'ates the positionV of: my new fiankarea and the nose radius. Thearrow E' indicates the large radius necessary' for lcon-- nectmg thequietmg zone Wlt'h the' nose radiusf ,on conventional constructions. ItWill be understood tlhatas the quieting zone is advanced, as indicatedby my new method, the

point 'of intersection of tangent lines is eX- tended thus permitting asmaller radius, in-

dicated by arrow F, to intersect withtlie nose radius. Not only has theflanlrradius been reduced to give quieter operation but the nose may bespread as indicated at G.

'These advantages, gained by advancing the inlet opening, permit a quietlift, and a valve which remains'open longer tlian heretofore.

i' 'The lines vforming the included angle .G are valve timing.

has been advanced as at 51k, the old opening spreadfrom-the top deadcenter line to give theprolonged valve opening, the amount of whichmaybe seen by the area of the figure formed by the outer full lines andthe dotted lines;

In, Fig. 5 the. bae line represents closed valve position, lines 28 and80 the opening and closing of the exhaust and intalie valvesi'espectively of my improved valve timing method. The dottedlinesindicatethe valve timing of a conventional construction and the 'line 26illustrates the pressure in the combustion Chamber, using the base lineto indicate atmospheric pressure. From this dlal gram it will be notedthat the intake Valve,

line 80, opens at 50 slig'htly after the depression has started and'thatthe exhaust valve,

line 28, closes at 52 before the end of the second compression period.Tlie usual practice heretofore has been to open the intake Valve afterthe second depression period or slightly before the end of the secondcompression period as at 52. l/Vhilethe illustration may not be true ofall coiistructions it is believed to be illustrative of the general ideaof previous The exliaust valve opening being at 56, and closes as at 52as compared with the old closing point 58. The intake valve opens at 50as coinpared to 52 and closes at 60 as coinpared to 62. It will be notedthat the distancev between 50 Aand 52 is greater than the distancebetween`60 and 62 showing the increase in time of opening of niymethodover the present practice. The line 64, thru the intersection oflines 28 and 30, indicates the point at which the valves trol the intakeand eXhaust valves. its design i's the basis of the results obtained. Ithas been found J[hat with'the eXhaustvalve opening the same lift.

ing at about 48 before bottom center the depression period starts, oratmospheric pressure is Vattained at about 28 or 30 before top centerand reaches its lowest pressure point at about 20' From thatpoint thepressure again builds up and goes above atmospheric at about before topcenter. Heretofore it has'been within these last 15- that the intakevalve has been opened and the blow back has been very noticeable. At,high speed the best results are obtained by opening the intake valve atthe time atmospheric pressure is reached approximately 80 before topcenter but for slow spee'ds it has been found that a betterl idle maybeobtained by opening the intake valve after .that period or approximatelyThis compensation is dependent upon engine design. The intakeV valvecloses at past bottom center. i

Referrin g now to the cam design, the intake cam has a nose spread of 8.The nose radius' is .218" and the flanke radius is 3.12 as compared to5.1 on a standard cam hav- The exhaust valve has va nose spread of 6,its nose radius is the same as the intake cam and its flank radius is3.12 as compared to 4.3 on a certain conventional cam. lWhile theeXhaust cam has not beenA modified' to the Vsame exteiit as the intakecam' itscfl'ankradius has been considerably reduced thereby making avery quiet oper-v ating cam. i

The included angle from the beginning of one flankiradius to the end ofthe oppositev fian'k radius, 2D' plus' G, is approximately 128 ascompared to 110 on the conventional cam. The quieting zone isVapproximately 30. The flank radius, v3.12, has ajproportion of 3 to`1With the distance from the'cen- I ter of the camshaft to the top of theflankv radius which is approximately one inch.

` The base circle is approXimately 1720. The cam'360-`-`(2 C' plus 2 D',120, plus G, 8) equals 1720V or the base circle of the cam' having (aconstantV radius throughout the 172.

lVhat I claiin is:

Vl. An internal combustionV engine having intake and exhaust passages, asingle carburetor adapted to supply combustible gases to saidintake'passages, valves for said intake and exhaust passages, avcamshaft adapt-` ed' to open said intake' valves not lessthan 15 beforeAtop center on the s'cavengingZ stroke and adapted to close the exhaustvalves,

after top center.

v2. An internal combustion engine havingV intake and exhaust passages, acarburetor adapted'to supply combustible gases to said intake passage,valves for'said intake and exhaust passages, and a cam havinga basecircle portion of less than 180 and a valve lifting portion greater than180 for opening said intake valve.

3. An internal combustion engine having

